Method for performing high-speed handover in base station cooperative wireless communication system, and device for same

Abstract

Disclosed in the present application is a method for a terminal to perform a handover in a wireless communication system. In particular, the method comprises the steps of: receiving a random access triggering signal from a serving cell; executing a random access procedure with a target cell on the basis of the random access triggering signal; receiving a downlink signal from the serving cell and transmitting an uplink signal to the target cell; receiving, from the serving cell, a message ordering a handover to the target cell; and transmitting, to the target cell, a predetermined message indicating the completed handover, on the basis of the message ordering a handover.

The invention claimed is: 
     
       1. A method for performing handover by a user equipment (UE) in a wireless communication system, the method comprising:
 receiving a random access triggering signal from a serving cell; 
 performing a random access procedure with a target cell based on the random access triggering signal; 
 receiving a downlink signal from the serving cell and transmitting an uplink signal to the target cell; 
 receiving, by the UE from a serving base station (BS), a handover command message indicating which commands the UE to perform handover to the a target cell from the serving cell BS, the handover command message including first information indicating whether a random access procedure to the target BS is to be skipped; 
 performing, by the UE, the handover to the target BS without performing the random access procedure to the target BS, based on that the first information indicates the random access procedure to the target BS is to be skipped; and 
 transmittinga prescribed, by the UE to the target BS based on a specific timing advance (TA), an uplink signal including a handover completion message indicating completion of that the handover to the target cell based on the handover command message BS is completed at the UE, 
 wherein the handover command message includes second information regarding a TA, based on that the first information indicates the random access procedure to the target BS is to be skipped, 
 wherein the UE obtains the specific TA from the second information regarding the TA in the handover command message based on that the first information indicates the random access procedure is to be skipped, 
 wherein the specific TA is a TA which has been used by the UE prior to the handover to the target BS and the second information indicates that the specific TA is to be reused for the target BS after the handover to the target BS, and 
 wherein the handover command message includes third information about a cell-radio network temporary identity (C-RNTI) to be used by the UE in the target BS. 
 
     
     
       2. The method according to  claim 1 , wherein the handover command message includes information indicating that the random access procedure is omitted. 
     
     
       3. The method according to  claim 2 , wherein the handover command message includes information about a temporary user equipment identity to be used by the user equipment in the target cell. 
     
     
       4. The method according to claim  2  1, wherein the handover command message includes information used for transmitting a scheduling request message by the user equipment UE to the target cell BS. 
     
     
       5. The method according to  claim 1 , wherein the serving cell is a macro base station and the target cell is a pico base station BS and the target BS are different eNodeBs (eNBs) in the wireless communication system. 
     
     
       6. The method according to  claim 1 , wherein the serving cell is a primary component carrier and the target cell is a secondary component carrier. 
     
     
       7. The method according to  claim 6 , wherein the secondary component carrier is reconfigured as the primary component carrier after the prescribed message is transmitted. 
     
     
       8. The method according to  claim 1 , wherein the prescribed handover completion message is related to a scheduling request message. 
     
     
       9. The method according to  claim 1 , wherein the a random access triggering signal is received through a physical control channel from the serving cell BS. 
     
     
       10. The method according to  claim 1 , further comprising:
 receiving a downlink signal from the target cell BS; and 
 transmitting an another uplink signal to the target cell BS, after transmitting the prescribed uplink signal including the handover completion message, 
 wherein a power control process of the user equipment UE is maintained before and after the prescribed handover completion message is transmitted. 
 
     
     
       11. The method according to claim 1, further comprising:
 monitoring, by the UE, a control channel signal of the target BS based on the C-RNTI included in the handover command message.   
     
     
       12. The method according to claim 11, wherein the uplink signal transmission is performed based on the control channel signal of the target BS. 
     
     
       13. The method according to claim 1, wherein the uplink signal transmission is performed based on the C-RNTI included in the handover command message. 
     
     
       14. The method according to claim 1, wherein the handover command message includes fourth information regarding an uplink resource allocated to the UE for transmission of the uplink signal to the target BS. 
     
     
       15. The method according to claim 1, further comprising:
 determining whether the handover to the target BS is successful or failed based on whether a control channel signal of the target BS is received within a predetermined time duration.   
     
     
       16. A non-transitory medium readable by a processor and recorded thereon one or more instructions that cause the processor to perform operations including:
 a reception procedure of a handover command message from a serving base station (BS), wherein the handover command message commands the processor to perform handover to a target BS, and the handover command message includes first information indicating whether a random access procedure to the target BS is to be skipped, second information regarding a timing advance (TA) based on that the first information indicates the random access procedure to the target BS is to be skipped, and third information about a cell-radio network temporary identity (C-RNTI) to be used by the processor in the target BS;   obtaining a specific TA from the second information regarding the TA in the handover command message based on that the first information indicates the random access procedure is to be skipped, wherein the specific TA is a TA which has been used by the processor prior to the handover to the target BS and the second information indicates that the specific TA is to be reused for the target BS after the handover to the target BS;   performing the handover to the target BS without performing the random access procedure to the target BS, based on that the first information indicates the random access procedure to the target BS is to be skipped; and   a transmission procedure of an uplink signal to the target BS based on the specific TA, the uplink signal including a handover completion message indicating that the handover to the target BS is completed at the processor.   
     
     
       17. A device for wireless communication, comprising:
 a radio frequency (RF) module; and   a processor controlling the RF module:   to receive, from a serving base station (BS), a handover command message which commands the device to perform handover to a target BS, the handover command message including first information indicating whether a random access procedure to the target BS is to be skipped,   to perform the handover to the target BS without performing the random access procedure to the target BS, based on that the first information indicates the random access procedure to the target BS is to be skipped, and   to transmit, to the target BS based on a specific timing advance (TA), an uplink signal including a handover completion message indicating that the handover to the target BS is completed at the device,   wherein the handover command message includes second information regarding a TA, based on that the first information indicates the random access procedure to the target BS is to be skipped,   wherein the processor obtains the specific TA from the second information regarding the TA in the handover command message based on that the first information indicates the random access procedure is to be skipped,   wherein the specific TA is a TA which has been used by the device prior to the handover to the target BS and the second information indicates that the specific TA is to be reused for the target BS after the handover to the target BS, and   wherein the handover command message includes third information about a cell-radio network temporary identity (C-RNTI) to be used by the device in the target BS.